Fire control instrument



Get. 19, 1943.

F. KowALsKx, JR

FIRE CONTROL INSTRUMENT Filed OCl'.. 16, 1941.

7 MM WM Patented Oct. 19, 1943 Frank Kowalski, Jr., United States Army,

Carthage, N. Y. Application October 16, 1941, Serial No. 415,246

(CLk ca -66) 10 Claims` (Granted under the act amendedV AprilA 30, 19

The invention described herein may be manufactured and used by or for the Government -for governmental purposes, without the payment to me of any royalty there-on.

This invention relates to a method and means for indirect re of guns, particularly machine guns, although the invention is adapted for the indirect ring of any size or type of gun.

Brieiiy the method comprises sighting on gun and target from the observation point, laying off distances on these lines of sight PTQDOTOHQI t their respective ranges and then determining the elevation, direction and length of the line joining the extremities of the laid-off distances, these readings yielding the necessary data at the gun itself.

The instrument is essentially a plotting board in three dimensions. The one shown by way of illustration is simple, compact and sturdy and will automatically and accurately obtain the three elements of indirect fire, namely, deection, angle of site, and range from gun to target. Having obtained the range from observation point to gun and' observation point to target with a range iinder, the three elements of indirect reare obtained automatically, without further data or computation by sighting the instrument from the observation point to the gun and from the observation point to the target.

It is therefore among the objects of the invention to provide an improved method of obtaining the elements necessary for indirect re and to provide an instrument of.' novel features for obtaining such elements.

The specific nature of the invention as well as other objects and advantages thereof willV clearly appear from a description of a preferred embodiment as shown in the accompanying drawing in which:

Figure 1 is a view of the instrument in elevation.

Figure 2 is a top plan view.

Figure 3 is a diagram showing the locations of the gun, target and observation point.

Figure 4 is a sectional view taken. on the 4 4 of Figure 2, and

Figure 5 is a sectional View taken on the line 5 5 of Figure 2.

Figure 6 is a section taken on the line 5-6 of Figure 1.

Referring to the drawing by characters or' reference, there is shown the head of a tripod or other supporting structure I for mounting an upright shaft 2. Rotatively carried by the shaft is a Collar 3 and this collar carries a horizontal line locks the cap of' March 3, 1883, as 28; .3"70` O. G'. 757-) arm 4, an upright 5iv and an arm 6 pivoted at I on the upright 5. Collar 3 and hence arm 4 and its system are rotated about upright shaft y by means of a worm 8. Shaft2 is held against-rotation by means ofa locking lever 9. Upright 5 together with arm 6 is rotatable withrespect to arm 4 by means of a worm l). A locking device for the worm gearing. is shown at II. The base It, housing the gearing It!v and holding slidable along arm 4 and locked in position by a set screw I 3. Hinged arm I3y is elevated or lowered by means of a. threaded` nipple I 4 carried` by a projection I5 on the upright 5.

Arm IB is hingedat I-'l to a cap i8- rotatively Seated on a sleeve I9 which in turn is received on a threaded portion of thel shaft 2. The sleeve I9 when rotated will hence the arm It. the arm It about A nipple 2lV serves to swing its pivot il. A set screw 22 I8 in position, and sleeve i9 is locked by means of a slotted section 23 and a bolt 24. A peep sight 25 is independently rotatable on a projection IB of the cap I3.

Upright 5Y carries a front sight 28 and arm i6 carries another front sight 2l'.

The arms 6 and Itv have opposed thin edges. 28 land 2S respectively and the sloping sides of the arms nearV the thin edges bear graduation marks. Arm 4` is likewise graduated to the same scale as arms B and I6.

The perpendicular distan-ce from the top of front sight 26 to the upper edge 28 ofv arm 6 isthe same as the perpendicular distances from the top of front sight 2l and' from the center of peep sight 25 to the bottom edge 2S of arm i6. Preferably pivot 'I will lie inthe line of the top edge 28 of arm 6 and pivot 'lV will lie in the line of the bottom edge 29 of arm I t, although the pivots may be located centrally of the arms in view of the small errors involved. Thus the line of edge 28 will always be approximately parallel to the plane determined bythe three sights. The parailelism is notl strict for the reason that front sight 2l is not always vertical as are the other two sights. It could be made so, as for instance by a universal mounting and counterweight for the sight, but if the elevations are not excessive and if the height cf sight 2'! above lower edge 25J is minimized, the errors will be negligible.

It will now be evident that arms 6 and I6 may be varied in azimuthV and elevation and that the i rear sight 25 may be raised and lowered as well as rotated. In addition, the upright 5 may be moved to and from the rear sight.

upright 5 is lift or lower the cap I3 and Operation To operate the instrument, upright 5 is moved to a position on arm 4 such that the distance from front sight 25 to rear sight 25 is proportional to the range from observation point to gun. The front sight 25 is next brought into the direction of the gun by rotating arm 4 with worm 8 and is then lined directly on the gun by raising or lowering rear sight 25 with sleeve I9 and then clamping the same with bolt 24. The instrument is now fixed as to range, direction and elevation of the line, observation point, to gun. Set screw 22 is now loosened and cap I8 together with arm IS is. rotated until front sight 21 is lined through the rear sight 25 on the target as to direction. With nipple 2|, arm I6 is raised or lowered until front sight 21 is lined through the rear sight onto the target as to elevation. The instrument is now xed as to direction and elevation of the line, observation point to target.

With rotating mechanism I0 and elevating nipple I4, the upper edge 28 of arm 6 is brought into contact with the lower edge 29 of arm I6 at a point on edge 29 distant from rear sight 25 an amount proportional to the range, observation point to target.

Since the rear sight 25 is freely rotatable, the lines, observation point to gun and observation point to target may be rechecked.

The angle on drum I2 gives the angle at the gun position from observation point to target. The range on arm 6 is proportional to the range from gun to target. The graduations may be such that the range is read directly. A clinometer placed on edge 28 of arm 6 will give the angle of site from gun to target. Arm S may also be graduated in mils so that instead of reading the range from gun to target, the angle of elevation in mils for the range from gun to target may be read directly thus obviating the need for reference to a range table.

In the diagram of Figure 3, O represents the rear sight, G the gun position and T the target. G is the position of the front sight 26 and T' is a point directly above the intersection of edges 28 and 29 on the line, observation point to target. Since the sides are respectively proportional and include a common angle the triangles are congruent and therefore GT is proportional to GT and angle OGT' is equal to angle OGT. Furthermore since parallel lines make equal angles With their projections on a plane, the clinometer reading on the edge 28 of the arm 6 (which, as shown above, is parallel to the plane of OGT) gives the same angle with the horizontal as GT, or angle of site of the line GT.

By incorporating a compass in the instrument it may be employed in a problem involving multiple observation po-ints. In the case where there is no convenient observation point from which both gun and target can be seen, the instrument is employed first at a point commanding the gun and then at a point commanding the target. `In this case the instrument is employed rst'to determine the range, angle of site and azimuth of the line from gun to second observation point. This will furnish the data for setting the line through peep sight 25 and sight 2B on the gun position, although the latter cannot be seen from the second observation point. The compass may be carried either on the drum under the shaft 5 or on the shaft under the peep sight 25. As shown, a compass 50 is carried on the drum concentric with the shaft 5 and contains a float 5I having a magnetic needle and dial whose North point is identical at 52. A pointer 53 on shaft 5 will indicate the azimuth thereof on said dial. After the sights of arm 4 have been aligned on the invisible gun the sights of arm I6 are trained on the target and the data from gun to target determined in the usual manner as from a single observation point.

The proper elevation from second observation point to gun is conveniently obtained by swinging sight 21 alongside sight 26, setting arm I6 with a clinometer and then adjusting peep sight 25. Clinometers may be permanently installed in arms 6 and I6.

Some advantages of the invention may be summarized as follows:

The new instrument replaces plane table, pencil, protractor, range table and aiming circle thus offering considerable improvement as to simplicity, weight and bulk. Fewer readings are necessary thus lessening the chance for personal error. No formulas are necessary to compute the angle of site and the elements of fire are obtained as fast as an aiming circle can obtain the bare data. Errors of arithmetic and algebra are obviated. The instrument is simple in principle and the method is readily taught. Firing problems can be worked in any kind of weather, and shelter is not required as is often the case when a plane table is used. Since the instrument is automatic, a probable error could be computed from it, and correction made by searching and traversing the gun within the limits of the probable error.

I claim:

l. A nre control apparatus comprising a mounting, a rear sight freely rotatable in azimuth thereon, a pair or arms extending laterally from said mounting and independently rotatable about a vertical line through said' rear sight, a front sight on each of said arms, and a thirdarm carried by one of said arms and adapted to intersect the angle between the pairs of arms.

2. A re control apparatus comprising a mounting, a rear sight freely rotatable in azimuth thereon, a pair of arms extending laterally from said mounting and independently rotatable about a vertical line through said rear sight, one of said arms being mounted for swinging motion in a vertical plane abo-ut a point in said vertical line through said rear sight, and a front sight on each of said arms.

3. A re control apparatus comprising a mounting, a rear sight freely rotatable in azimuth thereon, a pair of arms having front sights extending laterally from said mounting and independently rotatable about a vertical line through said rear sight, one of said arms being mounted for swinging motion in a vertical plane about a point in said vertical line through said rear sight, and an arm on the other of said arms mounted for swinging motion about a point in a vertical line through the front sight thereof and being rotatable in azimuth about said line.

4. In a iire contro-l apparatus as in claim 3, means for varying the radial position of the front sight on the second mentioned of said arms.

5. In a iire control apparatus as in claim 3, means for adjusting the angle of elevation of the iirst mentioned of said arms and of the third mentioned arm, respectively.

6. A iire control apparatus comprising a mounting, a vertical shaft on said mounting, an arm on said shaft extending laterally therefrom and rotatable thereabout, an assembly having an upright member and mounted on said arm for sliding motion thereon, means for rotating said upright, a front sight on said upright, a second arm extending from said upright and mounted for swinging motion in a vertical plane about a point in a vertical line through said front sight, means for varying the angle of elevation of said second arm, a third arm and holding means therefor mounted on said vertical shaft for rotation thereabout, a rear sight mounted for independent rotation o-n said holding means, means for raising and lowering said holding means and rear sight, a third arm carried by said holding means, extending laterally therefrom and mounted for swinging motion in a Vertical plane about a point in a vertical line through said rear sight, means for varying the angie of elevation of said third arm, a front sight on said third arm, said second and third arms being so constructed and arranged that when crossed and in Contact, one

edge of said second arm is parallel to the plane of the three sights.

7. A re control apparatus comprising a mounting, a rear sight freely rotatable in azimuth thereon, a pair of arms having front sights extending laterally from said mounting and independently rotatable about a vertical line through said rear sight, one of said arms being mounted for swinging motion in a vertical plane on, a pair of arms rotatable about a point in said vertical line through said rear sight, an arm on the other of said arms mounted for swinging motion about a point in a vertical line through the front sight thereof and being rotatable in azimuth about said line, and a compass concentric with one of said vertical lines.

8. A re control apparatus comprising a mounting, a rear sight freely rotatable in azimuth thereon, a pair of arms extending laterally from said mounting and independently rotatable about a vertical line through said rear sight, one of said arms being mounted for swinging motion in a Vertical plane about a point in said vertical line through said rear sight, a front sight on each of said arms, and a compass concentric with the sight on the other of said arms.

9. An angle and distance measuring instrument comprising a mounting, a rear sight thereon and about said mounting, one of said arms vbeing universally mounted, and a third arm universally mounted on the other of said pair of arms, and adapted to contact the rst-named universally mounted arm.

10. In an instrument as in claim 9, means to adjust the vertical angle of said universally mounted arms, respectively.

FRANK KOWALSKI, JR. 

